Quick mental math
- 10%: move the decimal one place left ($64.50 → $6.45).
- 20%: double the 10% figure.
- 15%: 10% plus half of it.
Many people tip on the pre-tax amount; check whether a service charge is already on the bill before adding a tip.
Frequently asked questions
How much is a 20% tip on $50?
$10, for a total of $60.
Last reviewed 2026-10-14.